Parâmetros De Qualidade Físico-químicos E Avaliação Da Atividade Antioxidante De Folhas De Plectranthus Barbatus Andr. (lamiaceae) Submetidas A Diferentes Processos De Secagem

This paper describes the physicochemical composition, the evaluation of the antioxidant activity by free DPPH radicals using the scavenging method, the determination of flavonoids and total phenolic compounds of ethanol, acetone and aqueous extracts of the medicinal plant Plectranthus barbatus Andr. (Lamiaceae), dehydrated in solar dryer and circulation oven at 60 °C. Water activity rates for two drying methods were below the minimum necessary for growth and toxin production of important food pathogens. Physicochemical results showed that both processes were effective in the dehydration of P. barbatus. The results demonstrated that the acetone (over) and ethanol (over and solar dryer) extracts showed the highest content of total phenols. The ethanol extract (over) showed the highest amount of flavonoids and better antioxidant activity (75.71 ± 10.57 µg L-1). © 2016, Instituto de Biociencias. All rights reserved.181485

Gyration radius of a circular polymer under a topological constraint with excluded volume

It is nontrivial whether the average size of a ring polymer should become smaller or larger under a topological constraint. Making use of some knot invariants, we evaluate numerically the mean square radius of gyration for ring polymers having a fixed knot type, where the ring polymers are given by self-avoiding polygons consisting of freely-jointed hard cylinders. We obtain plots of the gyration radius versus the number of polygonal nodes for the trivial, trefoil and figure-eight knots. We discuss possible asymptotic behaviors of the gyration radius under the topological constraint. In the asymptotic limit, the size of a ring polymer with a given knot is larger than that of no topological constraint when the polymer is thin, and the effective expansion becomes weak when the polymer is thick enough.Comment: 12pages,3figure

Adiabatic description of nonspherical quantum dot models

Within the effective mass approximation an adiabatic description of spheroidal and dumbbell quantum dot models in the regime of strong dimensional quantization is presented using the expansion of the wave function in appropriate sets of single-parameter basis functions. The comparison is given and the peculiarities are considered for spectral and optical characteristics of the models with axially symmetric confining potentials depending on their geometric size making use of the total sets of exact and adiabatic quantum numbers in appropriate analytic approximations

Parâmetros de qualidade físico-químicos e avaliação da atividade antioxidante de folhas de Plectranthus barbatus Andr. (Lamiaceae) submetidas a diferentes processos de secagem

RESUMO O presente trabalho descreve a composição físico-química, a avaliação da atividade antioxidante pelo método de sequestro de radicais livres DPPH, determinação de flavonoides e de fenóis totais dos extratos etanol, acetona e aquoso de Plectranthus barbatus Andr. (Lamiaceae), desidratadas em secador solar e em estufa de circulação de ar a 60 oC. Os valores de atividade de água encontrados para as duas secagens foram inferiores ao mínimo necessário para o crescimento e produção de toxina de patógenos de importância alimentar. Os resultados das análises físico-químicas demonstraram que ambos os processos mostraram-se eficientes na desidratação de P. barbatus. Os resultados demonstraram que os extratos acetona (estufa) e etanol (estufa e secador solar) foram os que apresentaram maior conteúdo de fenóis totais. O extrato etanólico (estufa) apresentou maior quantidade de flavonoides e melhor potencial antioxidante (IC50 = 75,71 ± 10,57 µg mL-1)